Muscular System Flashcards
What are the 3 Types of Muscles?
- Skeletal muscle
- Cardiac muscle
- Smooth muscle
- It is a long, cylindrical shaped muscles that is attached to bones.
- It is striated and multinucleated.
- Voluntarily controlled.
Skeletal muscles
Skeletal muscle can be classified based on how it attaches to bones. The two primary types of muscle attachment are what?
DIRECT
- In a direct attachment, the muscle fibers are directly attached to the bone, without an intervening tendon.
INDIRECT
- In indirect attachment, the muscle does not directly attach to the bone. Instead, the muscle fibers connect to a tendon or aponeurosis, which then attaches to the bone.
- It is branched shape and it is located in the heart.
- Striated and uninucleated. (This is not multinucleated like what the video says)
- The fibers are connected by intercalated discs, which contain gap junctions that allow for the rapid transmission of electrical signals between cells.
- Involuntarily controlled.
Cardiac muscles
- Muscle fibers are spindle-shaped and located in blood vessels, hollow organs.
- Uninucleated and non-striated.
- Involuntarily controlled.
Smooth muscle
It refers to the wave-like, rhythmic contractions of the smooth muscles in the walls of hollow organs, particularly in the digestive system. This movement is essential for propelling substances through tubes like the esophagus, intestines, and ureters (the tubes connecting the kidneys to the bladder).
Peristalsis or Peristaltic movement
What are the functions of the Muscular system?
- Movement
- Maintain posture
- Respiration
- Production of body heat
- Communication
- Heart beat
- Contraction of organs and vessels
What are the 4 Properties of Muscles?
- Contractility
- Excitability
- Extensibility
- Elasticity
It is the ability of muscle to shorten forcefully or contract.
Contractility
The capacity of muscle to respond to a stimulus.
Excitability
The ability to be stretched beyond its normal resting length and still be able to contract.
Extensibility
The ability of the muscle to recoil to its original resting length after it has been stretched.
Elasticity
How many percent of our body is muscles?
40%
It refer to the connective tissue layers and structures within skeletal muscles.
These layers help organize muscle fibers and provide the structural support needed for contraction and movement.
What are these? Note that there are 4.
- Epimysium
- Fascicles
- Perimysium
- Endomysium
It is the outermost layer of connective tissue that surrounds the entire muscle or whole muscle.
Epimysium
A skeletal muscle is subdivided into groups of muscle cells.
These are bundles of muscle fibers (cells) within a muscle.
Fascicles
It is the layer of connective tissue that surrounds each fascicle within a muscle.
Perimysium
It is a thin layer of connective tissue that surrounds each individual muscle fiber within a fascicle.
Endomysium
What is the cell membrane of a muscle fiber (muscle cell)?
Sarcolemma
The sarcolemma (cell membrane) has many tubelike inward folds, called _________.
Transverse tubules or T tubules
What are the Three (3) key components of the muscle fiber’s internal structure?
- Sarcoplasmic reticulum
- Terminal cisternae
- Muscle triad
It is an enlarged portions of the smooth endoplasmic reticulum in muscle cells.
It functions as a storage site for calcium ions (Ca²⁺), which are critical for muscle contraction.
Sarcoplasmic reticulum
It has a high concentration of calcium, which plays a major role in muscle contraction.
Sarcoplasmic reticulum
Are the enlarged end regions of the sarcoplasmic reticulum. They are located near the T-tubules and serve as the primary storage locations for calcium ions.
Terminal cisternae
It is a structural feature consisting of one T-tubule flanked by two terminal cisternae of the sarcoplasmic reticulum.
Muscle triad
It is the cytoplasm of a muscle fiber, which contains many bundles of protein filaments.
Sarcoplasm
It is the bundle of protein filaments.
Myofibrils
Note: Myofibrils consist of the myofilaments, actin, and myosin.
Myofibrils is consist of 3. What are these?
- Myofilaments
- Actin
- Myosin
It is the basic structural and functional unit of a skeletal muscle because it is the smallest portion of a skeletal muscle capable of contracting.
Sarcomere
Note: A sarcomere extends from one Z disks to the next Z disk.
These are the lines at each end of a sarcomere that mark the boundaries between adjacent sarcomeres.
It form a network of protein fibers that both serve as an anchor for actin myofilaments and separate one sarcomere from the next.
Z disks
These are alternating regions within a sarcomere that create the striated appearance of skeletal and cardiac muscle.
These bands correspond to the arrangement of thick and thin filaments within the sarcomere and are key to the muscle’s ability to contract and produce force.
I bands and A bands
It is the lighter region that extends toward the center of the sarcomere to the ends of the myosin and myofilaments.
It contains only thin filaments (actin), with no overlap of thick filaments (myosin).
I bands
This is the dark staining bands that extend the length of the myosin myofilaments.
A bands
Note: Actin and myosin myofilaments overlap for some distance on both ends of the A band and this overlap causes the contraction.
These are thin filaments within the sarcomere that are essential protein structures within muscle fibers that play a crucial role in the process of muscle contraction.
Actin myofilaments
Actin myofilaments are made up of 3 components. What are these?
- Actin
- Troponin
- Tropomyosin
It is a molecule that have binding sites for Calcium and tropomyosin filaments.
Troponin
It resemble bundles of tiny golf clubs.
Myosin filaments or thick myofilaments
It have ATP binding sites, ATPase, and attachment spots for actin.
Myosin heads
Troponin is a protein complex attached to tropomyosin at regular intervals along the actin filament.
It has three subunits. What does this stands for?
- TC
- TT
- TI
- TC - Troponin Calcium
- TT - Troponin Tropomyosin
- TI - Troponin Inhibitor
When calcium ions are released into the sarcoplasm during muscle excitation, they bind to troponin C (TC), causing the troponin complex to change shape. This shift in troponin moves tropomyosin away from the myosin-binding sites on actin, allowing myosin head to bind to actin and initiate contraction.
FAMILIARIZE ONLY
How does the myosin head move?
Through using ATP (Adenosine Triphosphate)
It is the electrical charge difference across the cell membrane of an unstimulated cell.
It is due to the inside of the membrane being negatively charged in comparison to the outside of the membrane being positively charged.
Resting membrane potential